Tape dispensers made to dispense moistened paper tape for strapping cartons, boxes and the like are well known. Examples of these dispensers are disclosed in U.S. Pat. No. 2,333,108 to Krueger et al, U.S. Pat. No. 2,333,109 to Krueger et al., U.S. Pat. No. 2,370,671 to Krueger et al., U.S. Pat. No. 2,409,872 to Krueger, U.S. Pat. No. 2,761,503 to Krueger, U.S. Pat. No. 2,990,991 to Sharpe, U.S. Pat. No. 2,994,464 to Krueger, U.S. Pat. No. 3,037,477 to Krueger et al., and U.S. Pat. No. 3,043,148 to Krueger. All of these patents are expressly incorporated herein by reference for their disclosure of the specific dispenser devices described therein.
The aforementioned prior art dispensers all have a similar structure, a typical example of which is shown in FIG. 3 of U.S. Pat. No. 2,994,464, reproduced herein as FIG. 1. The frame of the tape dispenser supports and optionally encloses a roll of dry paper tape 22. The tape is generally made of kraft paper which is coated with a water-activated adhesive on one side. The free end of the dry paper tape 24 is pulled through a feeding means, commonly constructed as two parallel feed rolls 28,30. The feed rolls 28,30, typically driven by a hand-operated lever or an electric motor 54, then push the tape along a path 26 through the rest of the dispenser, beneath a pressure plate 38 and over a moistened brush 36. After passing along this path the tape is automatically cut so that it can be easily removed by the user.
One limitation of this prior art system is that the tape must be sufficiently stiff to be pushed through the tape dispenser, yet still be sufficiently pliable after being wetted to easily conform and adhere to an often irregularly shaped box or package. Meeting both these requirements has been difficult for paper tape manufacturers. Yet stiff paper tapes and a weighted pressure plate have essentially solved this problem.
Due to the stiffness of traditional paper tape when dry, the pressure plate historically has been weighted to insure that the paper tape lays flat and is completely moistened as it travels between the pressure plate and the moistening brush. The weight is typically heated to help wet out the adhesive prior to its application to the package or carton.
New water-activated adhesive tapes have been developed recently that are quite dissimilar from traditional paper tapes in mechanical characteristics. Where the traditional paper tapes had a thickness of 7-8 mils, the new thin tapes average about 4-5 mils in thickness. Whereas conventional paper tapes required considerable weight and heat to conform to the moistening brush, the new thin tapes need relatively little weight and no heat. TRU-Seal tapes (using the TRU-TECH manufacturing process), made by Central Products Company of Linden, N.J., are one example of these new thin tapes.
These new thin tapes provide greater strength than prior art paper tapes, yet are more limp and supple than paper tape both when wet and dry. This increased suppleness poses a problem for those who would like to apply these tapes utilizing conventional tape dispensers. Due to their suppleness when dry, the new thin tapes lack the longitudinal rigidity necessary to be pushed through and ejected by such prior art tape dispensers. In practice, they buckle and jam in the paper path between the feed rolls and the pressure plate assembly.
Part of this problem is due to the pressure applied to the new tapes by prior art weighted and heated pressure plate assemblies. The new thin tapes are not as stiff as the old paper tapes and so do not need as much pressure or heat to become sufficiently wetted and activated. Because of the tape's lack of rigidity, the pressure between the pressure plate assembly and the moistening brush causes a great deal of frictional drag on the new thin tapes as the tape passes out of the machine from between the pressure plate assembly and the moistening brush.
Others have attempted to remedy the tape buckling and jamming problem by making major changes to the existing prior art tape dispensers. Better Pack, Inc., of Shelton, Conn., cures the problem by installing a complicated chute structure. This necessitates either a visit from a Better Pack technician, or sending the tape dispenser to Better Pack to be retrofitted.
It is also possible to utilize a more modern tape dispensing machine, such as the Marsh Ultra Gummed Tape Dispenser or the Better Pack models 754 or 755. However, many users have useful older machines, such as the Better Pack model 555L, and these would have to be discarded in favor of the new models at considerable cost.
What is needed, therefore, is a method for preventing tape jamming in conventional tape dispensers, such as the Better Pack Model 555L. Preferably, this method should include an apparatus which can be added to such conventional machines. Furthermore, this apparatus should be compatible with both the traditional paper tapes and the new thin tapes. The present invention provides one such solution to this problem.